Thesis (doctoral)--Friedrich-Alexanders-Universität Erlangen, 1894. / Cover title. Includes bibliographical references.

L’objet de cette étude est la représentation de l’architecture dans la peinture (ou architectura picta), en Égypte ancienne, à travers une étude de cas : la tombe comme motif iconographique au Nouvel Empire et au début de la Troisième Période intermédiaire.Après une mise au point sur les principes de représentation égyptiens et l’image architecturale en Égypte, dans toute sa diversité, l’étude porte sur l’évocation de la nécropole et des abords de la tombe dans l’iconographie. Une part importante de l’analyse est consacrée à la montagne en tant qu’objet figuré, notamment sa genèse à la XVIIIe dynastie, et aborde la question de la « représentation paysagère » en Égypte ancienne.L’architecture funéraire fait l’objet d’une mise en image à partir de la XVIIIe dynastie, dans le cadre de la représentation de rites funéraires sur les parois des tombes. Si les premières représentations sont conventionnelles et renvoient à l’architecture sacrée, elles intègrent au cours de la XVIIIe dynastie des éléments du réel, prenant pour modèle les tombes telles que se présentent au Nouvel Empire, c'est-à-dire des tombes pourvues d’une structure pyramidale. Cette image de la tombe à pyramide devient un motif du répertoire iconographique égyptien et perdure sur les cercueils et les papyri funéraires à la Troisième Période intermédiaire, après que les tombes à pyramide cessent elles-même d’exister. L’étude pose donc la question, en filigrane, du rapport au réel dans la peinture égyptienne, mais aussi de la fonction d’une telle image. / The study examines the representation of architecture in painting (or architectura picta) in ancient Egypt, through a case study of the tomb as an iconographical motif during the New Kingdom and the early Third Intermediate Period.After an overview of the principles of Egyptian representation and the architectural images in ancient Egypt, in all their diversity, the study focuses on the iconographical evocation of the necropolis and the tomb’s surroundings. An important part of this study concerns the mountain as an object of representation and in particular, its origins during the XVIIIth Dynasty, as well as dealing with landscape depictions in ancient Egypt.The funerary architecture is put in painting during the XVIIIth Dynasty, within depictions of funerary rites in private tombs. If the first tomb depictions refer to sacred architecture, according to representational conventions ; they show realistic elements in the course of the XVIIIth Dynasty, being modeled after the tomb architecture as it is during the New Kingdom, which is to say a pyramid-topped tomb. This tomb motif is integrated into the Egyptian iconographical repertoire and remains on coffins and funerary papyri, after the pyramid tomb itself disappeared from architecture in the Third Intermediate Period.The underlying question in this study is the relation to reality in Egyptian painting, but also the function of the tomb image.

Mammalian neurons rapidly undergo excitotoxic cell death during anoxia, while neurons from the anoxia-tolerant painted turtle can survive without oxygen for hours without apparent damage. An anoxia-mediated decrease in AMPA receptor currents are an important part of the turtle’s natural defence however the mechanism underlying it is unknown. Here I investigate a mechanism that involves activation of a mitochondrial KATP channel that subsequently signals a decrease in AMPAR currents. Whole-cell AMPAR currents were stable during normoxia, but anoxia or pharmacological activation of mKATP channels resulted in a 50% decrease in AMPAR currents. Conversely, mKATP antagonists blocked the anoxia-mediated decrease. Mitochondrial KCa channel modulators responded similarly. Blocking the Ca2+-uniporter also reduced normoxic AMPAR currents by 40%, and including BAPTA in the recording abolished the anoxia or agonist-mediated decrease. Therefore, the mKATP channel is involved in the anoxia-mediated down-regulation of AMPAR activity and is a common mechanism to reduce glutamatergic excitability.

Mammalian neurons rapidly undergo excitotoxic cell death during anoxia, while neurons from the anoxia-tolerant painted turtle can survive without oxygen for hours without apparent damage. An anoxia-mediated decrease in AMPA receptor currents are an important part of the turtle’s natural defence however the mechanism underlying it is unknown. Here I investigate a mechanism that involves activation of a mitochondrial KATP channel that subsequently signals a decrease in AMPAR currents. Whole-cell AMPAR currents were stable during normoxia, but anoxia or pharmacological activation of mKATP channels resulted in a 50% decrease in AMPAR currents. Conversely, mKATP antagonists blocked the anoxia-mediated decrease. Mitochondrial KCa channel modulators responded similarly. Blocking the Ca2+-uniporter also reduced normoxic AMPAR currents by 40%, and including BAPTA in the recording abolished the anoxia or agonist-mediated decrease. Therefore, the mKATP channel is involved in the anoxia-mediated down-regulation of AMPAR activity and is a common mechanism to reduce glutamatergic excitability.

Neonatal painted turtles (Chrysemys picta) spend their first winter inside the shallow, subterranean nest cavity where they completed embryogenesis. Consequently, hatchlings at high latitudes may be exposed to ice and cold during the winter. This study was undertaken to determine how long hatchlings withstand freezing at temperatures slightly below 0°C because tolerance for freezing has been proposed to be the key to survival by overwintering animals. A thermocouple was glued to the carapace of each hatchling. The animal was dipped in water to provide a site of nucleation of ice and was then placed into a glass jar that was partially immersed in a circulating bath at -2°C. Carapace temperature was monitored throughout the procedure. When a freezing exotherm was detected, timing of the freezing event began. Animals were maintained in a frozen state for 12-48 h prior to being warmed to room temperature. Of the 39 hatchlings, 22 did not survive, and mortality increased as the duration of freezing increased. Logistic regression indicates that no turtle would have survived in a frozen state for more than 54 h. These results indicate that hatchlings can survive only brief exposure to freezing of the body fluids. Thus, hatchlings cannot tolerate freezing during prolonged periods of cold.

Sex ratio theory suggests that the strength of intersexual selection will increase as a population more male-biased; reflecting increased selectivity in mate choice. Populations of pond turtle have varying adult sex ratios, in painted turtles (Chrysemys picta), reported sex ratios range from female biased (1:3) to male biased (3:1). I investigated the effect of sex ratio on male reproductive success (quantified as “fertilization success”) in painted turtles. I examined the mating system of painted turtles in a female-biased population using microsatellite paternity analysis, relating variation in male fertilization success to male phenotype and offspring survival, employed ex situ behavioural observation to clarify the mechanism behind the variation in male fertilization success and used agent-based modeling to simulate the effects of changing sex ratio, population density and proportions of male phenotype on male fertilization success. Small males contributed sperm to a greater number of clutches than did larger males, but were not more likely to reproduce in a season than larger males. There was no offspring fitness advantage related to male body size and no relationship between male claw length and fertilization success. Large male painted turtles courted at a higher frequency than small males. I found no relationship between male courtship behavior and claw length. Females showed no preference for males of any phenotype. Agent-based simulations were based on the distribution of best fit from the observed data; an amalgam of two Poisson distributions, each with its own probability of success and proportional representation in the final distribution. Increased female sex ratio bias, increased population density and increased proportions of “more successful” males all increased the mean and variance of male fertilization success, based on increased encounter rate among turtles. Small and large male painted turtles enjoy different fertilization success. It is uncertain whether this difference is based on active female choice, cryptic female choice, sperm competition or a combination of factors. Sex ratio simulations predict the opposite result as that predicted by sex ratio theory. These contrary results should be compared to simulations manipulating choosiness and field data from painted turtle populations to clarify mechanisms influencing male reproductive success.

The effect of incubation temperature on different morphological, physiological, cognitive and behavioral characteristics in reptiles is a well-studied topic, although the underlying mechanism leading to the differences between individuals incubated at different temperatures remains largely unknown. In this thesis I studied the effect of incubation temperature on cognitive abilities and the number of neurons and non-neuronal cells in the gecko Paroedura picta incubated at two different temperatures, 24řC and 30řC. The geckos were tested in two cognitive tasks with simulated predatory attack. 14-day-old hatchlings were tested in a Y-maze, while 6-months-old geckos were tested in an arena with shelters of different colors. After testing, the number of neurons and non- neuronal cells in several parts of the brain were estimated using the isotropic fractionator in selected individuals. Although incubation temperature did not affect the success in the cognitive task in hatchlings, it did affect the total time needed to find the shelter. This difference remained significant also in adult geckos. The number of neurons, which was used as a proxy for the information processing capacity of the brain, did not affect success in the cognitive tasks. However, absolute brain size correlated with success in the...

Mémoire numérisé par la Division de la gestion de documents et des archives de l'Université de Montréal.

Mémoire numérisé par la Division de la gestion de documents et des archives de l'Université de Montréal

Thesis (doctoral) - Ludwig-Maximilians-Universität München, 2003. / Includes bibliographical references.